There is a wireless entrance line using a wireless line as an entrance line, which is a transmission line that connects a base station and a host-side base station to each other, or connects base stations to each other. Application of this wireless entrance line to a wireless communication system is effective for turning an area, on which an optical line, an ISDN line or the like cannot be laid, to a communication area, and moreover, can reduce running cost of the wireless communication system by reducing maintenance cost since a wired communication system is not used.
For example, in Patent Document 1, a configuration is shown, in which a line control device and a base station are connected to each other by a wireless entrance line by providing a wireless relay station in such a case where the line control device and the base station cannot be connected to each other by a wired entrance line in a blind zone, a mountain range or the like, at which a radio wave from the base station cannot arrive.